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The problem of data storage is very important, but in practice it is a mistake. Often there will be discarded, locked and many other issues, seriously affecting the normal use of the overall system, so data-specific storage has become the market's most concerned about security products.
Data storage methods
In the current digital field, the most commonly used are the following four storage methods: hard disk, das, nas, san.
Hard drive
Whether it is dvr, dvs connected to the hard drive or server directly connected to the expansion of the way, are used hard disk storage. It should be said that the use of hard disk storage, and can not be counted as a strict sense of the storage system. The reason is the following:
First, it generally does not have a raid system, there is no redundancy for the data on the hard drive, even if it is through the host-side raid card or soft raid. Seriously affect the overall performance;
Second, its scalability is extremely limited. When the recording time exceeds 60 days, it often can not meet the storage requirements of recording time.
Third, data can not be stored centrally, post-maintenance costs are high, especially in the dvs hanging hard drive way, the maintenance costs often exceed the cost of acquisition within a year.
It should be said that hard disk storage is not suitable for large-scale digital video surveillance system applications. Especially the digital video monitoring system that needs long time recording. In general this approach is co-exist with other storage systems in the same system, as a buffer or emergency alternative to other storage.
2.das (direct attached storage)
das (direct attached storage), the full name for the direct connection of additional storage, the use of das way can be a very simple platform to achieve capacity expansion, while the data can provide a variety of rald level protection.
When using das way. Deploy the relevant hba card on the video storage unit. Used to set up a data channel with the storage device on the back end. The front of the video storage unit can be dvr, it can be a video storage server. The channel can be used optical fiber, ip network cable, sas cable even usb, 1394 lines.
The das method does not support simultaneous access of many video storage service units at the same time, and its capacity of expansion depends heavily on the capacity of its own storage expansion. So in a large digital video surveillance system, the application of das storage will cause great difficulty in system maintenance.
It is because of these characteristics of das storage, so this storage method is generally used for dvr expansion or small digital video surveillance project.
3.nas (network attached storage)
nas (network attached storage). The full name of the network attached storage, is a professional network file storage and file backup device, or network direct storage devices, network disk array. At the same time nas data can provide a variety of raid level of protection.
nas equipment and multiple video storage service units are connected through the ip network, according to tcp / ip protocol for communication, the file i / o (input / output) for data transmission. A nas unit includes the core processor, file service management tools, one or more hard drives for data storage.
Using nas mode can simultaneously support multiple host read and write at the same time, with excellent sharing performance and scalability; the same time, nas can be used in complex network environments. Deployment is also very flexible.
However, due to nas using cif / nfs protocol for file-level data transmission, so the network overhead is very large, especially when writing data bandwidth utilization is generally only between 20% -40%. So nas is generally used in small network digital video surveillance system or just for shared data storage.
4SAN (Storage Area Network)
SAN (storage area network), the full name of the storage area network, through the switch and other connected devices to connect the disk array and related servers high-speed private subnet. At the same time san can provide multiple raid levels of data protection.
san provides a dedicated, highly reliable storage network. Allowing to increase their storage capacity independently also simplifies management and centralized control, especially when all storage devices are brought together. It is precisely because of these characteristics, san architecture is particularly suitable for large network digital video surveillance system for storage applications, can handle thousands, tens of thousands of front-end monitoring point storage.
The current SAN is divided into FC SAN (Fiber Storage Area Network) and ip san (Ethernet Storage Area Network). The difference between them is the difference between connecting the line and using the data transfer protocol. Although the FC SAN due to the use of a dedicated protocol to ensure more stable transmission, and efficient, but its deployment, construction costs are much higher than ip san, so the current large network digital video surveillance system is more used ip san architecture .
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